(function() {
	var $backToTopTxt = "", $backToTopEle = $('<div class="gotop"></div>')
			.appendTo($("body")).text($backToTopTxt).attr("title",
					$backToTopTxt).click(function() {
						$("html, body").animate({
									scrollTop : 0
								}, 120);
					}), $backToTopFun = function() {
		var st = $(document).scrollTop(), winh = $(window).height();
		(st > 0) ? $backToTopEle.show() : $backToTopEle.hide();
		//IE6下的定位
		if (!window.XMLHttpRequest) {
			$backToTopEle.css("top", st + winh - 166);
		}
	};
	$(window).bind("scroll", $backToTopFun);
	$(function() {
				$backToTopFun();
			});
})();